validate method
Implementation
List<String> validate(String expectedAction) {
final errors = <String>[];
if (expectedAction == 'enter' && (planText == null || planText!.isEmpty)) {
errors.add('A reason is required when entering plan mode');
}
if (expectedAction == 'exit' && (planText == null || planText!.isEmpty)) {
errors.add('A plan summary is required when exiting plan mode');
}
return errors;
}